Struct CodeLayout 

pub struct CodeLayout {
    pub main_end: usize,
    pub func_region: Vec<(usize, usize)>,
    pub closure_ranges: Vec<(usize, usize)>,
    pub is_closure: Vec<bool>,
}

How the flat code stream partitions into functions.

Fields

main_end: usize

Main’s region end (exclusive): the first regular-function entry, or code.len().

func_region: Vec<(usize, usize)>

Per-function [start, end) in the code stream, holes included.

closure_ranges: Vec<(usize, usize)>

Every closure body’s [start, end) — the holes to excise from an enclosing region.

is_closure: Vec<bool>

is_closure[fi] — whether function fi is a closure body (a MakeClosure target).